I desperately need some help. I am running LibreOffice 5.1.4 on Ubuntu 14.04. All of a sudden it stopped working. Initially when I tried to open a file it would grey out and freeze. Now when I click on Calc, Writer etc nothing opens at all. I tried completely uninstalling and re-installing and it still does the same thing. Can anyone help or provide some guidelines for me?

Try deleting or renaming the LibreOffice user profile. I haven't a linux computer using LibreOffice in front of me, only one using OpenOffice, so my remarks are based on that and you may need to adjust them. Start your file manager to look at your Home directory. Then press Ctrl H to cause it to display hidden files. There should show (in a long list of hidden files/folders) ".openoffice" below this is a folder "4" and below that "user". Right click on that and select "rename" from the popup; renaming it to (say) "user.old". Now start up Open/LibreOffice. If you have done this correctly, OO/LibO should prompt you for your name/initials.

This may fix your problem.

Edit: Also worth starting the application in a terminal, which allows one to inspect error messages. For OO the command is "openoffice4" (no quotes)

There is a later version of gtk, but I read that it does not work well with the unity desktop. What I fail to understand is that I used libreoffice yesterday and it was working and today it doesn't work. I have completely uninstalled it an reinstalled. Everything works except for calc. When I try to open a spreadsheet/excel file it greys out and freezes. At the bottom left hand corner it says "calculating". It just hangs there.